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Groups > linux.debian.user > #210045

Re: IPv4 v IPv6

From Reco <recoverym4n@enotuniq.net>
Newsgroups linux.debian.user
Subject Re: IPv4 v IPv6
Date 2019-06-18 16:20 +0200
Message-ID <yan7P-5PN-1@gated-at.bofh.it> (permalink)
References (2 earlier) <ya0XD-FB-3@gated-at.bofh.it> <ya1TH-1el-1@gated-at.bofh.it> <yaj4d-3aX-3@gated-at.bofh.it> <yajGV-3D7-1@gated-at.bofh.it> <yakMG-4g3-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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	Hi.

On Tue, Jun 18, 2019 at 11:47:08PM +1200, Richard Hector wrote:
> On 18/06/19 10:32 PM, Reco wrote:
> > 	Hi.
> > 
> > On Tue, Jun 18, 2019 at 09:56:17PM +1200, Richard Hector wrote:
> >> On 18/06/19 3:38 AM, Reco wrote:
> >>> 	Hi.
> >>>
> >>> On Mon, Jun 17, 2019 at 10:38:27AM -0400, Gene Heskett wrote:
> >>>> But that opens yet another container of worms. If I arbitrarily assign 
> >>>> ipv6 local addresses, and later, ipv6 shows up at my side of the router, 
> >>>> what if I have an address clash with someone on a satellite circuit in 
> >>>> Ulan Bator.  How is that resolved, by unroutable address blocks such as 
> >>>> 192.168.xx.xx is now?
> >>>
> >>> More or less yes. It's called ULA (Unique Local Address) in IPv6 lingua.
> >>> If you're using anything from fd00:/8 - you're safe.
> >>
> >> As long as you choose them randomly. If you decide to use fd00::/64, or
> >> something else predictable, you may run into conflicts ... but only if
> >> you connect directly to their network.
> > 
> > No sensibly configured router will allow forwarding ULAs to the
> > internet.  A scenario you're describing is therefore impossible unless
> > one adds NAT66 or some kind of VPN to it. In the former case
> > predictability of site addresses do not matter, in the latter it's
> > solvable with the appropriate amount of custom routes.
> 
> Custom routes? When routing between 2 networks using the same range,
> either with a VPN or some kind of direct connection? It's going to need
> some evil double NAT sorcery, especially if the same actual addresses
> are in use on both.

As long as:

a) It's L3 VPN, so ARP is not a concern.
b) There are no duplicate IPs on both sites combined.

The problem can be 'solved' by announcing specific IP routes to each and
every host on both sites. Yes, it's gross.


> >> The main reason I'm using v6 is that 2 networks I'm running a VPN
> >> between both chose 192.168.1.0/24, and I can't change either ...
> > 
> > So? If your VPN is running in L3 mode it's still possible to add some
> > kludges to IPv4 routing. If your VPN passes L2 - you're doing it
> > terribly wrong.
> 
> Yes, I'm routing. Not sure what kludges you're proposing to let a
> machine at one end talk to a machine at the other which it thinks is on
> the same network.

See above, it ain't pretty.


> Adding v6 at both ends with properly unique ranges seemed much the saner
> option. Educational, as well :-)

I totally agree here.


> >> There are online random ULA generators - but I'm not convinced one of
> >> them didn't give me the same block twice, or whether it was my own error.
> > 
> > Never used one. IPv6 /8 block consists of 2^56 unique /64 subnets.
> > Surely it's possible to choose several unique /64 subnets by using, say,
> > ipv6calc.
> 
> Yes, but there is a recommendation to use random ones, and even a
> suggestion of how to do it, in RFC 4193.

But this RFC's "random" cannot mean "I start each day with selecting
new, custom /64 IPv6 ULA prefix for my site". ipv6calc fills this
nicely, try it some day.

Reco

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Thread

IPv4 v IPv6 mick crane <mick.crane@gmail.com> - 2019-06-17 11:10 +0200
  Re: IPv4 v IPv6 <tomas@tuxteam.de> - 2019-06-17 11:20 +0200
    Re: IPv4 v IPv6 Aidan Gauland <aidalgol@fastmail.net> - 2019-06-17 12:30 +0200
      Re: IPv4 v IPv6 Rob van der Putten <rob@sput.nl> - 2019-06-18 09:30 +0200
  Re: IPv4 v IPv6 Jonathan Dowland <jmtd@debian.org> - 2019-06-17 12:10 +0200
    Re: IPv4 v IPv6 Gene Heskett <gheskett@shentel.net> - 2019-06-17 16:40 +0200
      Re: IPv4 v IPv6 Dan Ritter <dsr@randomstring.org> - 2019-06-17 17:00 +0200
        Re: IPv4 v IPv6 Gene Heskett <gheskett@shentel.net> - 2019-06-17 18:30 +0200
        Re: IPv4 v IPv6 Gene Heskett <gheskett@shentel.net> - 2019-06-17 19:00 +0200
          Re: IPv4 v IPv6 Greg Wooledge <wooledg@eeg.ccf.org> - 2019-06-17 19:10 +0200
            Re: SOLVED was IPv4 v IPv6 discussion that went off the rails. Gene Heskett <gheskett@shentel.net> - 2019-06-18 02:10 +0200
          Re: IPv4 v IPv6 Dan Ritter <dsr@randomstring.org> - 2019-06-17 19:10 +0200
            Re: IPv4 v IPv6 Gene Heskett <gheskett@shentel.net> - 2019-06-17 19:40 +0200
              Re: IPv4 v IPv6 Dan Ritter <dsr@randomstring.org> - 2019-06-17 20:00 +0200
            Re: IPv4 v IPv6 Gene Heskett <gheskett@shentel.net> - 2019-06-17 20:00 +0200
            Re: IPv4 v IPv6 Pascal Hambourg <pascal@plouf.fr.eu.org> - 2019-06-18 14:50 +0200
              Re: IPv4 v IPv6 Greg Wooledge <wooledg@eeg.ccf.org> - 2019-06-18 14:50 +0200
                Re: IPv4 v IPv6 Pascal Hambourg <pascal@plouf.fr.eu.org> - 2019-06-18 15:10 +0200
          Re: IPv4 v IPv6 Dennis Wicks <wix@mgssub.com> - 2019-06-27 22:40 +0200
            Re: IPv4 v IPv6 Gene Heskett <gheskett@shentel.net> - 2019-06-27 23:30 +0200
        Re: IPv4 v IPv6 John Hasler <jhasler@newsguy.com> - 2019-06-17 20:30 +0200
          Re: IPv4 v IPv6 Dan Ritter <dsr@randomstring.org> - 2019-06-17 22:10 +0200
            Re: IPv4 v IPv6 Robin Hammond <rdhdroid@gmail.com> - 2019-06-17 22:20 +0200
              Re: IPv4 v IPv6 Andy Smith <andy@strugglers.net> - 2019-06-18 00:50 +0200
              Re: IPv4 v IPv6 John Hasler <jhasler@newsguy.com> - 2019-06-18 04:10 +0200
          Re: IPv4 v IPv6 Gene Heskett <gheskett@shentel.net> - 2019-06-18 02:20 +0200
      Re: IPv4 v IPv6 Reco <recoverym4n@enotuniq.net> - 2019-06-17 17:40 +0200
        Re: IPv4 v IPv6 Richard Hector <richard@walnut.gen.nz> - 2019-06-18 12:00 +0200
          Re: IPv4 v IPv6 Reco <recoverym4n@enotuniq.net> - 2019-06-18 12:40 +0200
            Re: IPv4 v IPv6 Richard Hector <richard@walnut.gen.nz> - 2019-06-18 13:50 +0200
              Re: IPv4 v IPv6 Reco <recoverym4n@enotuniq.net> - 2019-06-18 16:20 +0200
                Re: IPv4 v IPv6 Pascal Hambourg <pascal@plouf.fr.eu.org> - 2019-06-18 16:50 +0200
                Re: IPv4 v IPv6 Reco <recoverym4n@enotuniq.net> - 2019-06-18 18:20 +0200
                Re: IPv4 v IPv6 Linux Dave <mckisicd@gmail.com> - 2019-06-20 20:40 +0200
                Re: IPv4 v IPv6 Pascal Hambourg <pascal@plouf.fr.eu.org> - 2019-06-20 20:40 +0200
                Re: IPv4 v IPv6 Erwan David <erwan@rail.eu.org> - 2019-06-20 20:50 +0200
                Re: IPv4 v IPv6 Nicholas Geovanis <nickgeovanis@gmail.com> - 2019-06-20 21:00 +0200
                Re: IPv4 v IPv6 Reco <recoverym4n@enotuniq.net> - 2019-06-20 21:10 +0200
                Re: IPv4 v IPv6 Nicholas Geovanis <nickgeovanis@gmail.com> - 2019-06-18 17:40 +0200
                Re: IPv4 v IPv6 Reco <recoverym4n@enotuniq.net> - 2019-06-18 18:30 +0200
                Re: IPv4 v IPv6 Richard Hector <richard@walnut.gen.nz> - 2019-06-18 18:20 +0200
                Re: IPv4 v IPv6 Reco <recoverym4n@enotuniq.net> - 2019-06-18 18:30 +0200
      Re: IPv4 v IPv6 David Wright <deblis@lionunicorn.co.uk> - 2019-06-18 18:20 +0200
        Re: IPv4 v IPv6 Richard Hector <richard@walnut.gen.nz> - 2019-06-18 18:30 +0200
          Re: IPv4 v IPv6 Nicholas Geovanis <nickgeovanis@gmail.com> - 2019-06-18 18:40 +0200
          Re: IPv4 v IPv6 David Wright <deblis@lionunicorn.co.uk> - 2019-06-22 05:10 +0200
            Re: IPv4 v IPv6 Richard Hector <richard@walnut.gen.nz> - 2019-06-22 10:50 +0200
              Re: IPv4 v IPv6 David Wright <deblis@lionunicorn.co.uk> - 2019-06-24 20:20 +0200
            Re: IPv4 v IPv6 Andy Smith <andy@strugglers.net> - 2019-06-22 21:40 +0200
              Re: IPv4 v IPv6 Gene Heskett <gheskett@shentel.net> - 2019-06-22 22:50 +0200
                Re: IPv4 v IPv6 John Hasler <jhasler@newsguy.com> - 2019-06-22 23:40 +0200
                Re: IPv4 v IPv6 Gene Heskett <gheskett@shentel.net> - 2019-06-23 02:30 +0200
                Re: IPv4 v IPv6 John Hasler <jhasler@newsguy.com> - 2019-06-23 05:00 +0200
                Re: IPv4 v IPv6 Gene Heskett <gheskett@shentel.net> - 2019-06-23 08:30 +0200
                Re: IPv4 v IPv6 Pascal Hambourg <pascal@plouf.fr.eu.org> - 2019-06-23 11:20 +0200
              Re: IPv4 v IPv6 Andy Smith <andy@strugglers.net> - 2019-06-26 20:40 +0200
                Re: IPv4 v IPv6 Michael Stone <mstone@debian.org> - 2019-06-26 21:00 +0200
    Re: IPv4 v IPv6 Richard Hector <richard@walnut.gen.nz> - 2019-06-18 11:50 +0200
      Re: IPv4 v IPv6 Jonathan Dowland <jmtd@debian.org> - 2019-06-21 17:30 +0200
  Re: IPv4 v IPv6 andreimpopescu@gmail.com - 2019-07-02 11:10 +0200

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